1. Field of the Invention
This invention relates in general to oil well pumps and in particular to an improved standing valve assembly for a pump actuated by sucker rod.
2. Description of the Prior Art
In U.S. Pat. No. 3,143,080, all of which material is hereby incorporated by reference, an apparatus for improving the performance of a reciprocating oil well pump is disclosed. The pump is of the type having a plunger and traveling valve reciprocally carried in a cylindrical barrel at the bottom of the string of production tubing. The plunger is reciprocated by a string of sucker rod, pumping fluid on each upstroke.
A standing valve assembly is mounted above the plunger. The standing valve assembly includes a sub having a bore through which a piston is reciprocally carried. The piston connects the plunger to the sucker rod. The sub also has bores into which ball valves are secured. The valves in the sub close on the downstroke of the plunger, isolating the fluid in the production tubing from the plunger. The weight of the sucker rods and hydrostatic force on the piston urge the plunger downward. On the upstroke, the standing valves in the sub open to allow fluid pushed upward from the barrel to enter the column of fluid in the production tubing. The standing valves speed up the downstroke, increasing the performance of the pump.
Improvements to the apparatus shown in the above patent are desirable, however. The pumps manufactured under the above patent utilized resilient seals between the piston and the sub. Longer lasting and more effective sealing between the piston and sub are desirable. The standing valves mounted in the sub provided only a small area of fluid to pass upward. It is desirable to reduce fluid resistance through the standing valves by increasing the area through which the fluid can pass.